1. Field of the Invention
The present invention relates generally to printed circuit boards and, more particularly, to an attachment plate for directly mating printed circuit boards.
2. Related Art
Computer systems have one or more printed circuit boards on which various digital and/or analog components are mounted. The principal printed circuit board in a computer system is generally referred to as a motherboard. In personal computers, the motherboard is often called the system board or mainboard. Typically, the motherboard holds many of the digital components integral to the functioning of a computer system such as the CPU, memory and basic controllers. In many instances, additional circuit boards may be attached to the motherboard to provide additional functionality. Such additional circuit boards include expansion boards and daughtercards (also referred to as daughterboards). Expansion boards are circuit boards that plug into a computer's expansion slots. Expansions boards include, for example, controller boards, LAN cards and video adapters.
Daughtercards are typically attached directly to another printed circuit board such as the noted motherboard. In contrast to expansion boards, daughtercards access the motherboard components (memory and CPU) directly rather than through a slower expansion bus. Daughtercards typically include one or more integrated connectors, commonly referred to as a socket or header, which attach to an integrated connector on the motherboard. Once the integrated connectors are mated, the boards are typically joined by screws passing through holes in each circuit board.
A mating force generated by tightening the aforementioned screws urges the circuit boards toward each other, and serves to establish and maintain the physical and electrical connection between the boards. To maintain the circuit boards in relatively parallel planes, a number of appropriately-distributed spacers are sometimes used. The height of the spacers is approximately the same as the combined height of both integrated connectors when those connectors are fully mated.
Problems can arise when directly mating circuit boards such as the noted daughtercard and motherboard. If the force applied to the connectors during mating is not parallel to the pins and sockets of the connectors; for example, if the circuit boards are not maintained in parallel planes or laterally translate during mating, damage to the connector pins and sockets can easily result. One example of such a circumstance is when one or both of the circuit boards is not planar due to manufacturing imperfections, thermal cycling or other circumstances that can cause a printed circuit board to warp or curve. In this case, rotational or other non-axial forces can be placed on connector pins and sockets during mating. Under some circumstances, this can result in the bending of pins, incomplete electrical contact between some pins and their corresponding sockets, or other types of connection failures.